Description of the Prior Art
A bathtub drain stopper can, of course, be designed in such a manner that it is closed and opened by reaching into the tub and moving it. This is often considered objectionable. Consequently, it has been common to provide linkages that extend through the drain fitting and the overflow fitting, the operating lever or crank being mounted on an escutcheon plate that conceals, but does not block the opening to the overflow fitting.
Mechanisms of this type desirably include weights or springs to hold the operating lever and the associated mechanism in a stable manner either in open or closed position so that unwanted opening or closing is avoided. It has been common to provide an arrangement in which a pair of washers are mounted on the inner end of the lever with a coil spring in between and surrounding the lever. A cross pin on the lever holds the outer washer against separation from the lever. The inner washer rides on a cam formed on the inside of the escutcheon plate. The cam determines alternate stable positions, the cam having a central lobe that compresses the spring to a maximum. An improvement upon this arrangement is shown in U.S. Pat. No. 3,551,921 to W. R. Fox et al. in which a U-shaped spring takes the place of three separate pieces, namely the two washers and the coil spring. A cross pin is still required. In either arrangement, sliding friction on the cam lobes still must be overcome. The action may be rough.